Apparatus and method to provide breathing support

ABSTRACT

A ventilator, or a breathing assistance apparatus, is disclosed to ventilate patients who may have breathing difficulties, said device comprising a inspiratory pressure control duct configured to be immersed in a first body of fluid; a positive end-expiratory pressure control duct configured to be immersed in a second body of fluid; at least one valve connected to the peak inspiratory pressure control duct and to the positive end-expiratory pressure control duct, and at least one controller communicably connected to the valve to control rate of cycling of the valve, thereby controlling number of breaths per minute, and to control the duration of peak inspiratory pressure also known as inspiratory time.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/095,404, filed Apr. 11, 2016;

which is a continuation of U.S. patent application Ser. No. 14/468,320,filed Aug. 25, 2014, now U.S. Pat. No. 9,345,850, issued May 24, 2016;

which claims benefit of the earlier filing dates of U.S. ProvisionalPatent Application No. 61/874,323, filed Sep. 5, 2013, and U.S.Provisional Patent Application No. 61/929,947, filed Jan. 21, 2014;

and these patent applications are incorporated herein by reference.

FIELD

Embodiments described herein concern devices and methods that assist gasexchange and stabilize lung volume in patients of all ages withbreathing problems.

BACKGROUND

Patients who have breathing difficulties are conventionally providedbreathing assistance using mechanical ventilators. These devices aregenerally expensive and out of reach of a large portion of thepopulation, particularly in economically disadvantaged countries. Thesedevices also require substantial training and expertise to operate andmaintain. Further, these devices do not provide the user the ability toset and vary upper limit of safe positive pressure that is patientspecific and commensurate with the peak inspiratory pressure levels setduring ventilation in an easy and less expensive way using a fluidcolumn.

In recent years, there has been increasing interest in the developmentof breathing assistance devices that are less expensive. U.S. Pat. No.8,499,759 discloses the use of a two-way valve in a pressure regulatingbreathing assistance apparatus wherein the valve is placed intermediatetwo pressure control conduits that are submerged at varying lengths in asingle container containing a fluid. In such apparatus, depending on thesize of the valve, back pressure is generated whereby the pressure ofgas at a patient interface may be higher than the pressure set using oneof the control conduits, but not the other. This back pressure, if notcorrectly accounted for, has important treatment and safety implicationsif the device is used on a patient. Further, when two pressure controlconduits are located in the same container, the interaction between thetwo conduits in operation may impact pressures at a patient interface.

There is a significant need to provide a respiratory assistanceapparatus that is easy and less expensive to make, operate and maintain,and has high-positive-pressure safety feature that is simple, reliableand easily adjustable relative to the desired patient-specificinspiratory pressure level.

SUMMARY OF THE INVENTION

It is generally known in the medical profession that stabilization oflung volumes and improvement in gas exchange in patients receivingventilation assistance could be achieved through appropriate settingsand control of the positive pressures generated, amplitude and frequencyof oscillating positive pressure in the ventilator. Embodimentsdescribed herein provide the user a device and method to set pressures,oscillations, amplitude and frequency, and further allows the user toset the upper limit of positive pressure that is specific for a patientto reduce the likelihood of damage to the lungs. Additionally, theembodiments described herein maintain a patient's mean airway pressureat controlled levels. Device parameters such as levels of fluid in thecontainers, lengths of the ducts immersed in the fluids in thecontainers can be varied to control the high as well as low pressures.These embodiments also have features that allow a user to select andmodulate breaths per minute, inspiratory time, and the ratio ofinspiratory to expiratory time. The embodiments described herein areuseful to adults, children and newborn babies. Further, the embodimentscan be used during transport of patients, and may be used in facilitiesthat do not have access to mechanical ventilators. Several embodimentsdescribed herein can also be converted to a bubble Continuous PositiveAirway Pressure (CPAP) system.

In one embodiment, a ventilator system is provided having a pressurizedgas supply, two containers filled with fluid, and a primary duct withtwo ends—the proximal end and the distal end. The proximal end isconnected to the pressurized gas supply. The primary duct is adapted forconnection to a patient interface between the proximal and distal ends.At the distal end, a peak inspiratory pressure control duct is connectedand immersed in a body of fluid in the first container. A positiveend-expiratory pressure control duct is also connected to the distal endof the duct and immersed in the body of fluid in the second container. Atwo-port valve, also known as a two-way valve, is connected in betweenthe inspiratory pressure control duct and the positive end-expiratorypressure control duct wherein the rate of opening and closing of thevalve can be controlled. In addition, at least one safety duct isconnected to the primary duct near the proximal end and is immersed inthe fluid column in the first container at depth greater than theimmersed length of the peak inspiratory pressure control duct. Immersedlength is the vertical distance measured from the top of the fluidsurface to the tip of a pressure control duct. The depth to which the atleast one safety duct is immersed is controlled by the user. In someembodiments, ducts have simple markings, for example in cm of water, tohelp the user set high pressure (peak inspiratory pressure), lowpressure (positive end-expiratory pressure), and high-pressure limit(Pop-Off). In other embodiments, the immersed length is adjusted byvarying water column heights or by varying positions of ducts or both todeliver high and low pressures. In certain embodiments, as a safetyfeature, the default position of the ventilator system is to deliver thelower pressure at all times as CPAP when the ventilator system isconnected to the patient.

The use of double containers allows the user to isolate and fix anyissues with one container or duct without disconnecting the patient fromthe breathing support. Also, the use of double containers prevents thebubbles generated in one container from impacting the liquid columnlevel and pressure in the duct placed in the other container. In someembodiments, two-way or three-way valve allows the user to set breathingrates from 4-60 per minute, known as conventional mechanical breaths,and frequencies in the range of 60-900 per minute, known as highfrequency range. In other embodiments, a controller allows the user tocontrol inspiratory to expiratory ratios or have it fixed as percent ofcycle time to maintain a desired inspiration time to expiration timeratio, when the cycle frequencies are adjusted. Valves used in theembodiments include without limitation solenoid valves, pneumatic valvesand solar powered valves.

In another embodiment, a ventilator system is provided having apressurized gas supply, two containers filled with fluid, and a primaryduct with two ends—the proximal end and the distal end. The proximal endis connected to the pressurized gas supply. The primary duct is adaptedfor connection to a patient interface between the proximal and distalends. Also provided is a three-port valve (also known as a three-wayvalve) having one inlet port and two outlet ports. The distal end of theprimary duct is connected to the inlet port of the valve. The firstoutlet port of the valve is connected to a peak inspiratory pressurecontrol duct that is immersed in a body of fluid in the first container.The second outlet port of the valve is connected to a positiveend-expiratory pressure control duct that is immersed in a body of fluidin the second container. In operation, the valve alternatively connectsthe inlet port to the first outlet port and the second outlet port,i.e., the gas entering the inlet port passes through the first outletport for a period of time and then the gas entering the inlet portpasses through the second outlet port for another period of time,completing a cycle of passage of gas through the first outlet port andthe second outlet port. The cycle then repeats. A controllercommunicably connected to the valve controls the number of cycles perunit time, for example, number of cycles per minute. In addition, atleast one safety duct is connected to the primary duct near the proximalend and is immersed in the body of fluid in the first container at depthgreater than the immersed length of the peak inspiratory pressurecontrol duct.

In yet another embodiment, a second valve is also provided wherein thesecond valve is an open-shut type shutoff valve which can isolate thepositive end-expiratory pressure control duct from the remainder of theventilator gas flow circuit.

In some embodiments, the two containers are of the same size and thetips of the peak inspiratory pressure control and the positiveend-expiratory pressure control ducts are positioned at same locationwithin each of the two containers. The location is determined byvertical distance of the tip of a control duct from the bottom innersurface of a container. In this embodiment, the peak inspiratorypressure and the positive end-expiratory pressure are set by a user bychanging the fluid levels in the two containers.

In another embodiment, the level of fluid in the first container isgreater than the level of fluid in the second container such that theimmersed length of the peak inspiratory pressure control duct is greaterthan the immersed length of the positive end-expiratory pressure controlduct.

In certain embodiments, the fluid used is water. In other embodiments,the peak inspiratory pressure control duct and the end-expiratorypressure control duct are substantially circular having an insidediameter of between about 0.5 to 2 cm and their immersed lengths insidethe containers are in the range of about 2-50 cm.

DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a ventilator system utilizing a peak inspiratory pressurecontrol duct immersed in fluid in a first container; a positiveend-expiratory pressure control duct immersed in fluid in a secondcontainer; one two-port valve located in-between the peak inspiratorypressure control duct and the positive end-expiratory pressure controlduct; and the height of the column of fluid in the first container isgreater than the height of the column of fluid in the second container.Based on the durations of valve open and shut times, low as well highfrequency breathing support can be delivered at fixed or variable ratioof inspiratory to expiratory time.

FIG. 2 depicts a ventilator system utilizing a peak inspiratory pressurecontrol duct immersed in fluid in a first container; a positiveend-expiratory pressure control duct immersed in fluid in a secondcontainer; one two-port valve located in-between the peak inspiratorypressure control duct and the positive end-expiratory pressure controlduct; one high pressure safety duct immersed in fluid in the firstcontainer at a depth greater than the immersed length of the peakinspiratory pressure control duct; and the height of the column of fluidin the first container is greater than the height of the column of fluidin the second container.

FIG. 3 depicts a ventilator system as shown in FIG. 1 with angledportions added to the peak inspiratory pressure control duct and thepositive end-expiratory pressure control duct.

FIG. 4 depicts a ventilator system as shown in FIG. 2 with angledportions added to the peak inspiratory pressure control duct and thepositive end-expiratory pressure control duct and one high pressuresafety duct immersed in fluid in the first container at a depth greaterthan the immersed length of the peak inspiratory pressure control duct.

FIG. 5 depicts a ventilator system utilizing a peak inspiratory pressurecontrol duct immersed in fluid in a first container; a positiveend-expiratory pressure control duct immersed in fluid in a secondcontainer; one three-port valve connected to the peak inspiratorypressure control duct, the positive end-expiratory pressure control ductand a primary duct; and the height of the column of fluid in the firstcontainer is greater than the height of the column of fluid in thesecond container.

FIG. 6 depicts a ventilator system utilizing a peak inspiratory pressurecontrol duct immersed in fluid in a first container; a positiveend-expiratory pressure control duct immersed in fluid in a secondcontainer; one three-port valve connected to the peak inspiratorypressure control duct, the positive end-expiratory pressure control ductand a primary duct; one high pressure safety duct immersed in fluid inthe first container at a depth greater than the immersed length of thepeak inspiratory pressure control duct; and the height of the column offluid in the first container is greater than the height of the column offluid in the second container.

FIG. 7 depicts a ventilator system as shown in FIG. 5 with angledportions added to the peak inspiratory pressure control duct and to thepositive end-expiratory pressure control duct.

FIG. 8 depicts a ventilator system as shown in FIG. 6 with angledportions added to the peak inspiratory pressure control duct and to thepositive end-expiratory pressure control duct and one high pressuresafety duct immersed in fluid in the first container at a depth greaterthan the immersed length of the peak inspiratory pressure control duct.

FIG. 9 depicts a ventilator system utilizing a peak inspiratory pressurecontrol duct immersed in fluid in a first container; a positiveend-expiratory pressure control duct immersed in fluid in a secondcontainer; a first valve that is a two-port valve located in-between thepeak inspiratory pressure control duct and the positive end-expiratorypressure control duct; a second valve that is an on-off shutoff valvelocated in-between the peak inspiratory pressure control duct and thetwo-port valve; one high pressure safety duct immersed in fluid in thefirst container at a depth greater than the immersed length of the peakinspiratory pressure control duct; and the height of the column of fluidin the first container is greater than the height of the column of fluidin the second container.

FIG. 10 depicts a ventilator system utilizing a connector tointerconnect the peak inspiratory pressure control duct with thehigh-pressure safety duct.

FIG. 11 depicts a ventilator system utilizing a peak inspiratorypressure control duct immersed in fluid in a container; a positiveend-expiratory pressure control duct immersed in fluid in the samecontainer; one three-port valve connected to the peak inspiratorypressure control duct, the positive end-expiratory pressure control ductand a primary duct; a controller communicably connected to the valve;and immersed length of the peak inspiratory pressure control duct isgreater than immersed length of the positive end-expiratory pressurecontrol duct.

FIG. 12 depicts a ventilator system utilizing a peak inspiratorypressure control duct immersed in fluid in a container; a positiveend-expiratory pressure control duct immersed in fluid in the samecontainer; one two-port valve located on the positive end-expiratorypressure control duct; one two-port valve located on the peakinspiratory pressure control duct; a controller communicably connectedto both the valves; and immersed length of the peak inspiratory pressurecontrol duct is greater than immersed length of the positiveend-expiratory pressure control duct.

DETAILED DESCRIPTION

Embodiments described herein provide the user a device and method to sethigh and low pressures, oscillations, amplitude and frequency andfurther allows the user to set the upper limit of positive pressure thatis specific for a patient to reduce the likelihood of damage to thelungs. Device parameters such as levels of fluid in the containers,lengths of the ducts immersed in the fluid in the containers can bevaried to control the pressures. These embodiments also have featuresthat allow the user to select and modulate breaths per minute,inspiratory time, and the ratio of inspiratory to expiratory time. Theembodiments described herein are useful for patients of all agesincluding adults, children and newborn babies. Further, the embodimentscan be used during transport of patients of all ages and in facilitiesthat do not have access to mechanical ventilators. In operation,pressurized gas is released from the gas supply into the primary duct ofthe ventilator system disclosed in FIGS. 1-12, and the gas is deliveredto a patient

FIG. 1 illustrates a patient ventilation system 100 having a pressurizedgas supply 102, two containers 104 and 106 filled with fluid, and aprimary duct 108 with two ends—the proximal end 110 and the distal end112. The proximal end 110 is connected to the pressurized gas supply102. The duct 108 is adapted for connection to a patient interface 114between the proximal end 110 and distal end 112. At the distal end 112,at least one peak inspiratory pressure (PIP) control duct 116 isconnected and immersed in a body of fluid 118 in the first container104. At least one positive end-expiratory pressure (PEEP) control duct120 is also connected to the distal end 112 of the duct and immersed inthe body of fluid 122 in the second container 106. A two-port valve 124is connected in between the inspiratory pressure control duct and thepositive end-expiratory pressure control duct. The valve 124 cycles fromopen to shut position and back to open position, and the rate of cyclingof the valve can be controlled by a controller (not shown) communicablyconnected to the valve. The failure mode of the valve 124 is the openposition whereby the gas flow is directed to the positive end expiratorypressure (PEEP) control duct 120 and the pressure at the patientinterface 114 is maintained at the lower or baseline level.

In one embodiment, the two containers 104 and 106 are of the same heightmeasured from the bottom inner surface of the container to the topopening of the container, and the distal ends (tips) of the peakinspiratory pressure control duct 116 and the positive end-expiratorypressure control duct 120 are at same vertical distance from the fromthe bottom inner surfaces of the two containers 104 and 106respectively. The level of fluid in the first container 104 is greaterthan the level of fluid in the second container 106 whereby immersedlength which is the vertical distance measured from the top of the fluidsurface to the tip of a pressure control duct is greater for the peakinspiratory pressure control duct 116 than for the positiveend-expiratory pressure control duct 120. In other embodiment, theheight of the container 104 is greater than the height of container 106.In yet another embodiment, the level of fluid in container 104 is aboutthe same as the level of fluid in container 106.

In certain embodiments, the two containers are identical in shape andsize, and the ducts are pre-positioned in the containers at identicallocations. The advantage of having identical containers with identicallypositioned PIP and PEEP control ducts is the ease of fabrication andoperation. In other embodiments, the two containers are similar in shapeand size and the ducts are pre-positioned in the containers at similarlocations. In certain embodiments, the peak inspiratory pressure controlduct and the end-expiratory pressure control duct are substantiallycircular having an inside diameter of between about 0.5-3 cm and theimmersed length inside the containers is in the range of about 2-50 cm.The immersed vertical length of PIP and PEEP control ducts can bemeasured as the vertical distance from the fluid surface to the distalends of the ducts. In all embodiments, the immersed vertical length ofthe PIP and PEEP control ducts can be adjusted to any value by adding orremoving fluid to adjust fluid level, by sliding the ducts up and downto adjust the duct location, or doing both.

In some embodiments of the PIP and PEEP control ducts, the diameters ofthe ducts are about 0.5 cm to 2 cm. In other embodiments, more than onePIP control duct and more than one PEEP control duct may be used. In yetother embodiments, the PIP and PEEP control ducts may each havesubstantially similar lengths and diameters or different lengths anddiameters. The lengths and cross-sectional shapes of the primary duct,the PIP control duct, and the PEEP control duct are preferably short andsubstantially circular or slightly oval in shape. However, any or all ofthe ducts can have any length or cross-sectional shape including but notlimited to square, rectangular, triangular etc., without departing fromthe spirit of the present disclosure.

The fluid may comprise any number of suitable fluids or liquidsexhibiting a wide range of densities, masses and viscosities includingbut not limited to water, or water with added vinegar to reduce thelikelihood of bacterial contamination of the water.

A gas supply provides pressurized medical grade gas to the ventilatorsystem including to the primary duct, patient duct, PIP control duct andPEEP control duct. Gas delivered by the gas supply may compriseatmospheric gases or any combination, mixture, or blend of suitablegases, including but not limited to atmospheric air, oxygen, nitrogen,helium, or combinations thereof. The gas supply may comprise a gascompressor, a container of pressurized gases, a substantially portablecontainer of pre-pressurized gases, a gas-line hookup (such as found ina hospital) or any other suitable supply of pressurized gas, orcombinations thereof. The gas supply is preferably controlled orconfigured to have a variable gas flow rates that can be controlled byuser and adjusted according to the individual requirements of eachpatient. The patient ventilation system or gas supply may also includeone or more flow control devices (not shown) including but not limitedto a mechanical valve, an electronically controlled mechanical valve, arotameter, a pressure regulator, a flow transducer, or combinationsthereof. Gas flow rates, which are commonly used in the art, typicallyrange from about 2 liters/minute (L/min) to about 15 L/min. However,these embodiments allow any flow rates of gas set by the user. Forexample, larger patients may require larger gas flows. Increasing theflow rates could result in the delivery of higher pressures; however, bysetting the high-pressure blow-out level of the safety duct to a safelevel, one can avoid inadvertent delivery of excessively high pressuresto the patient.

A Heat and Moisture Exchanger (not shown) can also be included in thepatient ventilation system to control the temperature and humidity ofgas delivered to the patient interface. Continuous flow of gas in thedelivery duct also prevents the patient from re-breathing gases exhaledfrom the lungs.

Referring to FIG. 1, the patient interface 114 can be invasive ornon-invasive, including but not limited to face or nasal masks, nasalprongs, nasal cannula, short tube(s) placed in the nasal ornaso-paharynx, endotracheal tubes, tracheostomy tubes, or combinationsthereof. The two-port valve 124 may comprise a mechanical orelectromechanical valve. The two-port valve 124 may be electronicallycontrolled or mechanically controlled such that the user is able to setthe ventilation rate and inspiratory time or the ratio of inspiratory toexpiratory time. The two-port valve 124 is preferably “normally open”such that in the event of failure the valve would remain open and thepatient would be subjected to the lower or baseline pressure. When thetwo-port valve 124 is open, gases flow through PEEP control duct 120,which is set in the container 106 with lower level of fluid than thecontainer 104 having the PIP control duct 116, thereby controlling thepositive end expiratory pressure in the circuit. When the two-port valve124 is closed, gas in the pressurized circuit flows through PIP controlduct 116, which is set in a container 104 with higher level of fluidthan the container 106 having the PEEP control duct 120, thereby raisingthe pressure to peak inspiratory pressure and delivering a “mandatorybreath” to the patient. The valve 124 can then be opened again to allowthe patient to exhale, and the process may be repeated. In this manner,a patient can receive peak inspiratory pressure and positive endexpiratory pressure (Bi-PAP ventilation) or intermittent positivepressure ventilation (IPPV). In some embodiments, any number of valves,PIP control ducts and PEEP control ducts can be used to providedifferent levels of high and low pressures.

FIG. 2 illustrates a ventilator system similar to FIG. 1, but has inaddition, at least one safety duct 230. The safety duct 230 is connectedto the primary duct 208 near the proximal end 210 of the primary duct208. The safety duct 230 is immersed in the body of fluid 218 in thefirst container 204 at depth greater than the immersed length of thepeak inspiratory pressure control duct 216. The safety duct allowssetting the limit of a safe pressure relative to the set PIP pressure.For example, in some embodiments the fluid used is water, and thedifference in vertical distance between the tip of the immersed safetyduct 230 and the immersed PIP control duct 216 can be set at 5 cm if theuser wants the maximum pressure that the lungs may be subjected to benot greater than the set PIP pressure by 5 cm of water.

FIG. 3 illustrates a patient ventilator system similar to thatillustrated in FIG. 1 utilizing a PIP control duct 316 in the firstcontainer 304 and a PEEP control duct 320 in the second container 306.The ducts 316 and 320 are immersed in fluid and configured to modulateairway pressures in a patient receiving Bi-PAP or IPPV. The embodimentillustrated in FIG. 3 further comprises two angled sections 332 and 334connected to the distal ends of the PIP and PEEP control ductsrespectively. The angle of angled section may be altered between 0 and180 degrees to the vertical to control the amplitude and frequency ofairway pressure oscillations that are superimposed on top of the airwaypressure wave form for both the inhalation and exhalation cycles. Insome embodiments, the angled arm of the angled section has length ofbetween 2 cm and 10 cm. In other embodiments, more than two angledsections may be used. In one embodiment, the angles of the two or moreangled sections may be substantially similar. In other embodiments, theangles of the two or more angled sections may be different. In oneembodiment, the diameter of the angled section is the same as thediameter of the PIP and PEEP control ducts. In another embodiment, thediameter of the angled section is different from the diameter of the PIPand PEEP control ducts. The immersed vertical length of PIP and PEEPcontrol ducts can be measured as the vertical distance from the fluidsurface to the elbow of the angled section.

FIG. 4 illustrates a ventilator system similar to FIG. 3, but has inaddition, at least one safety duct 430. The safety duct 430 is connectedto the primary duct 408 near the proximal end 410 of the primary duct408. The safety duct 430 is immersed in the body of fluid 418 in thefirst container 404 at depth greater than the immersed length of thepeak inspiratory pressure control duct 416.

FIG. 5 illustrates a patient ventilator system 500 having a pressurizedgas supply 502, two containers 504 and 506 filled with fluid, and aprimary duct 508 with two ends—proximal end 510 and distal end 512. Theproximal end 510 is connected to the pressurized gas supply 502. Theprimary duct 508 is adapted for connection to a patient interface 514between the proximal end 510 and distal end 512. A three-port (alsoknown as three-way) valve 525 is provided with one inlet port and twooutlet ports. The distal end 512 is connected to the inlet port of thethree-port valve 525. The first outlet port of the valve 525 isconnected to at least one peak inspiratory pressure (PIP) control duct516 that is immersed in a body of fluid 518 in the first container 504.The second outlet port of the valve 525 is connected to at least onepositive end-expiratory pressure (PEEP) control duct 520 that isimmersed in the body of fluid 522 in the second container 506. In oneembodiment, the two containers 504 and 506 are of the same heightmeasured from the bottom inner surface of the container to the topopening of the container, and the distal ends (tips) of the peakinspiratory pressure control duct 516 and the positive end-expiratorypressure control duct 520 are at same vertical distance from the bottominner surfaces of the two containers 504 and 506 respectively. The levelof fluid in the first container 504 is greater than the level of fluidin the second container 506 whereby immersed vertical length as measuredfrom the top of the fluid surface to the tip of a pressure control ductis greater for the peak inspiratory pressure control duct 516 than forthe positive end-expiratory pressure control duct 520. In otherembodiment, the height of the container 504 is greater than the heightof container 506. In yet another embodiment, the level of fluid incontainer 504 is about the same as the level of fluid in container 506.

The valve 525 cycles between the first outlet port and the second outletport thereby continuously switching the flow of gas from the inlet portto the first outlet port and the inlet port to the second outlet port.Each cycle corresponds to one breath. In operation, when the gas flowsfrom the inlet port to the first outlet port of valve 525, gas flowsthrough PIP control duct 516, which is set in the container 504 withhigher level of fluid than the container 506 having the PEEP controlduct 520, thereby controlling the PIP in the circuit. When the gas flowsfrom the inlet port to the second outlet port of valve 525, gas in thepressurized circuit flows through PEEP control duct 520, which is set ina container 506 with lower level of fluid than the container 504 havingthe PIP control duct 516, thereby lowering the pressure to PEEP andallowing the patient to exhale. The valve 525 can then cycle back to thefirst outlet port to allow the patient to receive PIP, and the cycle maybe repeated. In this manner, a patient can receive peak inspiratorypressure and positive end expiratory pressure (Bi-PAP ventilation) orintermittent positive pressure ventilation (IPPV).

In one embodiment, rate of cycling (measured in cycles per minute) ofthe valve 525 is controlled using a controller (not shown) communicablyconnected to the valve. In another embodiment, controller allows user toset time T1 (Inspiratory Time) during which gas flows from the inletport to the first outlet port and time T2 (Expiratory Time) during whichgas flows from the inlet port to the second outlet port. In oneembodiment, T1 is set as time in seconds. In another embodiment, T1 orT2 can be set as a fraction of cycle time or as a ratio of T1 and T2such that the sum of T1 and T2 equals time of one cycle. Because the PIPcontrol duct is connected to the first outlet port and the PEEP controlduct is connected to the second outlet port, T1 is inspiratory time andT2 is expiratory time of a cycle or breath. In one embodiment, theexpiratory time T2 is set to be greater than inspiratory time T1, andthe ratio T2/T1 is greater than 1. The ratio of inspiratory time andexpiratory time may be depicted as T1:T2 and the ratio shown as 1:Nwhere, in one embodiment, N is a number greater than 1. In anotherembodiment, the controller does not allow the value of N to be lessthan 1. In another embodiment, breaths per minute (bpm) and inspiratorytime (T1) in seconds are set by the user, and the controller calculatesexpiratory time (T2) in seconds using the formula T2=(60/bpm)−T1. In yetanother embodiment, if the calculated expiratory time (T2) in seconds isless than the inspiratory time (T1) in seconds set by the user, thecontroller sets T1=T2=30/bpm. In another embodiment, controller allowsthe user to control the ratio of inspiratory time T1 to expiratory timeT2 or have T1 fixed as percent of cycle time to maintain a desiredinspiration time to expiration time ratio. For example, if T1 is set as33% of cycle time, then T2 will be 67% of cycle time, giving T1:T2 ratioof 1:2. In another embodiment, the controller is integrated with thevalve, with the control logic embedded in the valve. In one embodiment,the failure mode of the valve 525 is the open position to the secondoutlet port whereby the gas flow is directed to the PEEP control duct520 and the pressure in the ventilator system is maintained at thebaseline, i.e. lower level. In another embodiment, if the controllersets the cycling rate of the valve 525 as zero, the valve remains in theopen position to the second outlet port whereby the gas flow is directedto the PEEP control duct 520 and the pressure in the ventilator systemis maintained at the baseline i.e. lower level. In another embodiment,if power to the valve 525 is shut off, the valve remains in the openposition to the second outlet port whereby the gas flow is directed tothe PEEP control duct 520 and the pressure in the ventilator system ismaintained at the baseline i.e. lower level. Thus the apparatus can beconverted from Bi-PAP ventilation to bubble CPAP by simply shutting offpower to the valve or setting cycling rate of the valve to zero.

FIG. 6 illustrates a ventilator system similar to FIG. 5, but has inaddition, at least one safety duct 630. The safety duct 630 is connectedto the primary duct 608 near the proximal end 610 of the primary duct608. The safety duct 630 is immersed in the body of fluid 618 in thefirst container 604 at depth greater than the immersed length of thepeak inspiratory pressure control duct 616. The safety duct allowssetting the limit of safe pressure relative to the set PIP pressure. Forexample, in some embodiments the fluid used is water, and the differencein vertical distance between the tip of the immersed safety duct 630 andthe immersed PIP control duct 616 can be set at 5 cm if the user wantsthat the maximum pressure that the lungs may be subjected to not begreater than the set PIP pressure by 5 cm of water.

FIG. 7 illustrates a patient ventilator system similar to thatillustrated in FIG. 5 utilizing a PIP control duct 716 in the firstcontainer 704 and a PEEP control duct 720 in the second container 706.The ducts 716 and 720 are immersed in fluid and configured to modulateairway pressures in a patient receiving Bi-PAP or IPPV. The embodimentillustrated in FIG. 7 further comprises two angled sections 732 and 734connected to the distal ends of the PIP and PEEP control ductsrespectively. The angle of angled section may be altered between 0 and180 degrees to the vertical to modify the amplitude and frequency ofairway pressure oscillations that are superimposed on top of the airwaypressure wave form for both the inhalation and exhalation cycles. Insome embodiments, the angled arm of the angled section has length ofbetween 2 cm and 10 cm. In some embodiments, more than two angledsections may be used. In other embodiments, the angles of the two ormore angled sections may be substantially similar. In still otherembodiments, the angles of the two or more angled sections may bedifferent.

FIG. 8 illustrates a ventilator system similar to FIG. 7, but has inaddition, at least one safety duct 830. The safety duct 830 is connectedto the primary duct 808 near the proximal end 810 of the primary duct808. The safety duct 830 is immersed in the body of fluid 818 in thefirst container 804 at depth greater than the immersed length of thepeak inspiratory pressure control duct 816.

FIG. 9 illustrates a ventilator system similar to that in FIG. 2, buthas a second valve 926 as an additional safety. The second valve 926 isprovided in between the peak inspiratory pressure control duct 916 andthe two-port valve 924 wherein the second valve 926 is an open-shut typeshutoff valve that can isolate the valve 924 and the positiveend-expiratory pressure control duct 920 from the primary duct 908 andthereby from the remainder of the ventilator gas flow circuit. Theisolation of the valve 924 may be necessary if there is a catastrophicfailure of the valve 924. The shutting of the shutoff valve 926 alsoallows the user to employ the ventilator system as a bubble CPAP system.

In addition to the safety duct illustrated in FIGS. 2, 4 and 6, someembodiments can include additional safety features (not shown) such as ahigh pressure “pop-off” or “pop-open” safety valve to protect thepatient from receiving airway pressures greater than a pre-determinedthreshold to reduce the likelihood of high pressures reaching thepatient in the unlikely event that the patient circuit is occludedbetween the patient and the gas exiting the system through the fluidcontainer. The pop-off valve provides a second level of protection whenthe safety duct such as duct 230 in FIG. 2 is present in the ventilatorsystem. The pressure level setting of pop-off valve will be generallyhigher than the blow-out pressure setting of the safety duct. Notehowever that pop-off safety valve is generally pre-set to certain valuesand does not provide user the flexibility provided by the safety duct,which allows setting the limit of safe pressure relative to the set PIPpressure.

In an embodiment shown in FIG. 10, which illustrates a ventilator systemsimilar to that in FIG. 2, the safety duct 230 is interconnected usingconnector 233 with the PIP control duct 216 whereby the user can adjustthe vertical spacing between the tip of the PIP control duct 216 and thetip of the safety duct 230 by sliding the connector or in incrementalsteps of the connector, thereby providing safety of a measured fluidcolumn height above the PIP pressure for blow out of pressurized gas incase of a pressure surge in the ventilator system. In certainembodiments, the fluid is water and the user can adjust the tip of thesafety duct 230 relative to the tip of the PIP control duct 216 suchthat the high pressure limit (pop off) is in the range of 0 to about 15cm water column above the PIP pressure. In the embodiment shown in FIG.10, the level of fluid 218 in container 204 is about the same as thelevel of fluid 222 in container 206, but the levels of fluid in the twocontainers could also be different as shown in the embodiments describedbefore. In certain embodiments as shown in FIG. 10, the distal ends(tips) of the peak inspiratory pressure control duct 216 and thepositive end-expiratory pressure control duct 220 are at differentvertical distances from the bottom inner surfaces of the two containers204 and 206, respectively.

Some embodiments can include a low-pressure “pop-open” or one-way valve(not shown) to protect the patient from receiving airway pressures lowerthan a pre-determined threshold, for example sub-atmospheric pressures.In this manner, the one-way valve can help prevent a lung fromcollapsing, help prevent the patient from inhaling fluid, and helpprevent the patient from re-breathing exhaled gases. Fresh gas ofcontrolled concentration (not shown) can also be supplied to the one-wayvalve.

FIG. 11 illustrates a patient ventilator system having a pressurized gassupply 502, a container 505 filled with fluid, and a primary duct 508with two ends—the proximal end 510 and the distal end 512. The proximalend 510 is connected to the pressurized gas supply 502. The primary duct508 is adapted for connection to a patient interface 514 between theproximal end 510 and distal end 512. A three-port (also known asthree-way) valve 525 is provided with one inlet port and two outletports. The distal end 512 is connected to the inlet port of thethree-port valve 525. The first outlet port of the valve 525 isconnected to at least one peak inspiratory pressure (PIP) control duct517 that is immersed in a body of fluid 523 in the container 505. Thesecond outlet port of the valve 525 is connected to at least onepositive end-expiratory pressure (PEEP) control duct 521 that isimmersed in the body of fluid 523 in the container 505. The immersedvertical length as measured from the top of the fluid surface to the tipof a pressure control duct is greater for the PIP control duct 517 thanfor the PEEP control duct 521. The valve 525 cycles between the firstoutlet port and the second outlet port thereby continuously switchingthe flow of gas from the inlet port to the first outlet port and theinlet port to the second outlet port. Each cycle corresponds to onebreath. In one embodiment, rate of cycling (measured in cycles perminute) of the valve 525 is controlled using a controller 515communicably connected to the valve. In another embodiment, controller515 allows user to set time T1 during which gas flows from the inletport to the first outlet port and time T2 during which gas flows fromthe inlet port to the second outlet port. In one embodiment, T1 is setas time in seconds. In another embodiment, T1 or T2 can be set as afraction of cycle time or as a ratio of T1 and T2 such that the sum ofT1 and T2 equals time of one cycle. Because the PIP control duct isconnected to the first outlet port and the PEEP control duct isconnected to the second outlet port, T1 is inspiratory time and T2 isexpiratory time of a breath. In one embodiment, the expiratory time T2is set to be greater than inspiratory time T1. In another embodiment,breaths per minute (bpm) and inspiratory time T1 in seconds are set bythe user, and the controller calculates expiratory time T2 in secondsusing the formula T2=(60/bpm)−T1. In yet another embodiment, if thecalculated expiratory time T2 in seconds is less than the inspiratorytime T1 in seconds set by the user, the controller 515 setsT1=T2=30/bpm. In another embodiment, controller 515 allows user tocontrol the ratio of inspiratory time T1 to expiratory time T2 or haveT1 fixed as percent of cycle time to maintain a desired inspiration timeto expiration time ratio. In another embodiment, the controller 515 isintegrated with the valve, with the control logic embedded in the valve.In one embodiment, the failure mode of the valve 525 is the openposition to the second outlet port whereby the gas flow is directed tothe PEEP control duct 520 and the pressure in the ventilator system ismaintained at the baseline i.e. lower level. In another embodiment, ifthe controller 515 sets the cycling rate of the valve 525 as zero, thevalve remains in the open position to the second outlet port whereby thegas flow is directed to the PEEP control duct 520 and the pressure inthe ventilator system is maintained at the baseline, i.e. lower level.In another embodiment, if power to the valve 525 or the controller 515is switched off, the valve remains in the open position to the secondoutlet port whereby the gas flow is directed to the PEEP control duct520 and the pressure in the ventilator system is maintained at thebaseline, i.e. lower level.

FIG. 12 illustrates a patient ventilation system having a pressurizedgas supply 102, a container 105 filled with fluid, and a primary duct108 with two ends—the proximal end 110 and the distal end 112. Theproximal end 110 is connected to the pressurized gas supply 102. Theduct 108 is adapted for connection to a patient interface 114 betweenthe proximal end 110 and distal end 112. At the distal end 112, at leastone peak inspiratory pressure (PIP) control duct 117 is connected andimmersed in a body of fluid 123 in the container 105. At least onepositive end-expiratory pressure (PEEP) control duct 121 is alsoconnected to the distal end 112 of the duct and immersed in the body offluid 123 in the container 105. The immersed length of the PIP controlduct 117 is greater than the immersed length of the PEEP control duct121. A two-port valve 109 is placed on the PIP control duct 117 and islocated between the PIP control duct 117 and the distal end 112 of theprimary duct. Another two-port valve 125 is placed on the PEEP controlduct 121 and is located between the PEEP control duct 121 and the distalend 112 of the primary duct. The valves 109 and 125 cycle from open toshut position and back to open position, and the rate of cycling of thevalves can be controlled by a controller 115 communicably connected tothe valves 109 and 125. The valves 109 and 125 are controlled by thecontroller 115 such that when the valve 109 is open, the valve 125 isclosed and when the valve 109 is closed, the valve 125 is open.

In operation, when the two-port valve 125 is open and the two-port valve109 is closed, gases flow through PEEP control duct 121, therebycontrolling the PEEP in the circuit. When the two-port valve 125 isclosed and the two-port valve 109 is open, gases in the pressurizedcircuit flows through PIP control duct 117, thereby raising the pressureto peak inspiratory pressure. The valve 125 can then be opened again andvalve 109 closed to allow the patient to exhale, and the process may berepeated. In this manner, a patient can receive peak inspiratorypressure and positive end expiratory pressure (Bi-PAP ventilation) orintermittent positive pressure ventilation (IPPV).

More embodiments concern methods of using one or more of theaforementioned combinations to assist the breathing of a subject (e.g.,an adult, child, infant human being or another mammal). By someapproaches, a subject having breathing problems is identified orselected and said subject is connected to one or more of the devicesdescribed herein. In some embodiments the subject is attached to thedevice by nasal prongs and in other embodiments, the subject is attachedto the device by face or nasal masks, tube(s) placed in the nasopharynx,endotracheal tubes, tracheostomy tubes, or combinations thereof. Oncethe subject and device are connected, gas flow is initiated. Preferablegas flows for infants are about 1 to 10 L/min, whereas adults mayrequire gas flows of about 1 to 30 L/min and large mammals may require 1to 100 L/min or more. Optionally, the frequency, amplitude of cyclingpressure, or volume of gas delivered is monitored so as to adjust thebreathing assistance for the particular subject. In some embodiments, adevice having a particular immersed length of the peak inspiratorypressure duct, immersed length of the positive end-expiratory pressureduct, diameter or cross-sectional area of PIP and PEEP control ducts, orparticular fluid can be selected for a subject's unique needs. That is,in some embodiments, a patient in need of breathing assistance isselected or identified and a breathing assistance device, as describedherein, is selected or identified according to a subject's age, size, ortherapeutic need.

Some embodiments include a method for providing continuous positiveairway pressure with oscillating positive end-expiratory pressure to asubject by providing any of the devices or apparatuses described herein,releasing gas from the gas supply into the apparatus and delivering thegas to the subject. Other embodiments include a method for increasingthe volume of gas delivered to a subject by providing any of thebreathing assistance devices or apparatuses described herein, adjustingthe angle of the distal end of the duct with respect to a vertical axisand releasing gas from the gas supply into the apparatus to deliver gasto the subject. In some embodiments, the distal end of the duct isadjusted to an angle greater than or equal to between about 91-170degrees. In other embodiments, the distal end of the duct is adjusted toan angle of about 135 degrees with respect to a vertical axis.

Example 1

This example describes the ventilator system used and experimentsperformed to test the system described in FIG. 1. A lung machinemanufactured by Ingmar Medical, Pittsburgh, Pa. (www.ingmarmed.com) wasconnected at patient interface of the ventilator system. A two-port(two-way) solenoid valve manufactured by MAC Valves, Inc., Wixom, Mich.(www.macvalves.com) was used in the system. The open-shut cycle of thevalve was controlled using an electronic timer made by IDEC Corporation,Sunnyvale, Calif. (us.idec.com). Compressed air and air/oxygen mixtureswere used in the tests. The tubing used was the standard 10 mm tubingused with conventional ventilator systems in a hospital setting. Thefluid in the containers was water at room temperature. The pressure atthe patient interface was measured using a manometer manufactured byLife Design Systems, Inc., Madison, Wis. The manometer had a range of−20 cm water to +80 cm water in increments of 1 cm water. Tests were runfor gas flow rates from 0.5 L/min through 5 L/min in increments of 0.5L/min, and from 5 L/min through 15 L/min in increments of 1 L/min. Thegas flow rate was set using flowmeter manufactured by Precision Medical,Northampton, Pa. (www.precisionmedical.com). The immersed length of thePIP control duct was varied from 10 to 30 cm of water, and the immersedlength of the PEEP control duct was varied from 2 to 10 cm of water. Thecycling of the valve was done from 1 cycle per minute to 60 cycles perminute. Each cycle corresponds to a breath and thus the tests wereconducted from 1 breath per minute to 60 breaths per minute.

The valve offers a resistance to flow of gas, resulting in a loss ofpressure. The loss of pressure due to the resistance of valve increasedas the flow rate of gas was increased. At gas flow rates of 15 L/min, apressure loss as high as 4 cm water was observed in the valve, resultingin a back pressure whereby observed PEEP at patient interface was about4 cm of water higher than that set by the PEEP control duct in thesecond container. Because the PIP control duct did not have a valve inthe line of flow from the patient interface to the PIP control duct, thePIP setting did not experience the back pressure from the valve.Therefore, depending on the flow rate of gas, a correction to accountfor the back pressure of the valve had to be made to the PEEP controlduct. When the back pressure was 4 cm of water, a correction of 4 cm tothe immersed length of the PEEP control duct in the second container wasmade such that actual immersed length was 4 cm less than the requiredPEEP at the patient interface. Thus if the required PEEP at the patientinterface is 10 cm of water and the back pressure is 4 cm of water, thenimmersed length of PEEP control duct is 6 cm.

For comparison, tests were also conducted using a single containercontaining water wherein both the PIP and PEEP control ducts wereimmersed in one and the same container, as disclosed in U.S. Pat. No.8,499,759, and the disclosure of U.S. Pat. No. 8,499,759 is incorporatedherein by reference in its entirety. The bubbles from one duct had animpact on observed pressure from the other duct when the PIP and PEEPcontrol ducts were in the same container. This impact was morepronounced at higher gas flow rates and less pronounced when thediameter of the container was increased. It was found that all otherconditions remaining the same, the observed pressure at the patientinterface was closer to the pressure set by the control ducts when thetwo control ducts were in different containers (as in FIG. 1) comparedwith the observed pressures when the control ducts were in the samecontainer (as in U.S. Pat. No. 8,499,759). Further, it was found that,for a given gas flow rate, correction to account for back pressure inPEEP control duct is similar whether the two control ducts were placedin one container or in two separate containers.

Example 2

The system in Example 1 was modified to include a safety duct as shownin FIG. 2. The safety duct was set at a pressure 3 cm of water above thePIP pressure. The primary duct was intentionally squeezed at the distalend to simulate occlusion of the duct and the safety duct released thepressure buildup when the pressure at the patient interface reached 3 cmof water above the PIP pressure. The tests were repeated successfully atdifferent pressure levels.

Example 3

This example describes the ventilator system used and experimentsperformed to test the system described in FIG. 5. A lung machinemanufactured by Ingmar Medical, Pittsburgh, Pa. (www.ingmarmed.com) wasconnected at patient interface of the ventilator system. A three-port(three-way) solenoid valve manufactured by MAC Valves, Inc., Wixom,Mich. (www.macvalves.com) was used in the system. The size of thethree-port valve was the same as the two-port (two-way) valve used inExample 1. The cycling of the valve was controlled using an electronictimer made by IDEC Corporation, Sunnyvale, Calif. (us.idec.com).Compressed air and air/oxygen mixtures were used in the tests. Thetubing used was the standard 10 mm plastic tubing used with conventionalventilator systems in a hospital setting. The fluids in the containerswere water at room temperature. The pressure at the patient interfacewas measured using a manometer manufactured by Life Design Systems,Inc., Madison, Wis. The manometer had a range of −20 cm of water to +80cm of water in increments of 1 cm water. Tests were run for gas flowrates from 0.5 L/min through 5 L/min in increments of 0.5 L/min, andfrom 5 L/min through 15 L/min in increments of 1 L/min. The gas flowrate was set using flowmeter manufactured by Precision Medical,Northampton, Pa. (www.precisionmedical.com). The immersed length of thePIP control duct was varied from 10 to 30 cm of water, and the immersedlength of the PEEP control duct was varied from 2 to 10 cm of water. Thecycling of the valve was done from 1 cycle per minute to 60 cycles perminute. Each cycle corresponds to a breath and thus the tests wereconducted from 1 breath per minute to 60 breaths per minute.

Similar to the back pressures observed in Example 1, at gas flow ratesof 15 L/min, a back pressure as high as 4 cm. of water was observed inthe valve. But unlike the performance observed for the system in FIG. 1of Example 1 wherein the PEEP at the patient interface was affected byback pressure but the PIP at patient interface was not affected by backpressure, the three-port valve resulted in back pressure that affectedsimilarly both PIP and PEEP as observed at the patient interface. Boththe PIP control duct and the PEEP control duct had the three-port valvein the line of flow from the patient interface to respective controlducts, whereby correction to account for back pressure of the valve hadto be made to both the PEEP control duct and the PIP control duct. For agiven gas flow rate, the correction was similar for both the PIP controlduct and the PEEP control duct. When the back pressure was 4 cm ofwater, a correction of 4 cm to the immersed length of the PEEP controlduct was made such that actual immersed length of the PEEP control ductwas 4 cm less than the required PEEP at the patient interface. Andsimilarly a correction of 4 cm to immersed length of the PIP controlduct was made such that actual immersed length of the PIP control ductwas 4 cm less than the required PIP at the patient interface. Thus ifthe required PEEP at the patient interface is 10 cm of water, therequired PIP at the patient interface is 30 cm of water, and the backpressure is 4 cm of water, then the immersed length of PEEP control ductis 6 cm and the immersed length of the PIP control duct is 26 cm. Achart was prepared that showed relationship between flow rate of gas inL/min and correction in cm. of water.

The back pressure from the valve is primarily due to size the valve(e.g., diameter of valve orifice through which gas passes, diameter ofinlet and outlet passage ways and ports of valve) that createsresistance to flow of gas. The smaller the orifice size, e.g., smallerthe diameter, the higher the resistance. To minimize the back pressureand the resulting correction to immersed length of PIP control duct andPEEP control duct, the size of orifice, the size of internal passageways, the size of the ports are preferably the same as or similar to thesize of the ventilator tubing. The pressure loss in the valve can becalculated using a coefficient of flow (Cv) of the valve. Thecalculation method is generally known. The pressure loss decreases asthe Cv value increases. The gas is a compressible fluid and the Cv valueand pressure loss of gas depends on temperature and pressure of the gas.The pressure of the gas in the ventilator system is slightly aboveatmospheric (2-50 cm of water above atmospheric) and the temperature ofthe gas in the ventilator system may be kept slightly above roomtemperature and could be as high as 40 degrees Celsius. For the gaspressure and temperature that are generally prevalent in a ventilatorsystem, the coefficient of flow Cv of the valve is preferably greaterthan about 1.5 and more preferably greater than about 2.

Example 4

Tests were conducted using the valve, timer and tubing system of Example3, but using a single container containing water wherein both the PIPcontrol duct and the PEEP control duct were immersed in water as shownin FIG. 11. The test parameters such as gas flow rates, immersed lengthsof PIP and PEEP control ducts, cycling rates of valve were same as thosein Example 3. The bubbles from one duct had an impact on observedpressure from the other duct when the PIP control duct and the PEEPcontrol duct were in the same container. The impact was more pronouncedat higher gas flow rates and less pronounced when the diameter of thecontainer was increased. It was found that, all other conditionsremaining the same, the observed pressure at the patient interface wascloser to the pressure set by the control ducts when the two controlducts were in different containers compared with the observed pressureswhen the control ducts were in the same container. When back pressuresin Example 3 were compared with back pressures in Example 4, it wasfound that, for a given gas flow rate, correction to account for backpressure is similar for both PIP control duct and PEEP control ductirrespective of whether the two control ducts were placed in onecontainer or in two separate containers.

Example 5

This example describes the ventilator system used and tests performedusing a system as shown in FIG. 12 wherein two two-port valves were usedto determine whether two two-port valves would replicate the system andtests done in Example 4 where a single three-port valve was used. Twotwo-port solenoid valves manufactured by MAC Valves, Inc., Wixom, Mich.were used in the system. The first two-port solenoid valve was placed onthe PIP control duct and is located between the PIP control duct and thedistal end of the primary duct. The second two-port solenoid valve wasplaced on the PEEP control duct and is located between the PEEP controlduct and the distal end of the primary duct. The test parameters werethe same as those in Examples 3 and 4. The two valves were controlledsuch that when the first valve was open, the second valve was closed andwhen the first valve was closed, the second valve was open. The twotwo-port valves were identical and their size including valve apertureand port diameters was the same as that of the three-port valve used inExample 4. The observed performance of the system in Example 5 wassimilar to the performance of the system in Example 4. Unlike in Example1 where a single two-port valve is used and correction to account forback pressure was greater than zero for the PEEP control duct and zerofor the PIP control duct, in Example 5 the back pressure correction wasfound to be greater than zero and similar for both the PIP control ductand the PEEP control duct.

It will be appreciated that several of the above-disclosed and otherfeatures and functions, or alternatives or varieties thereof, may bedesirably combined into many other different systems or applications.Also that various alternatives, modifications, variations orimprovements therein may be subsequently made by those skilled in theart which are also intended to be encompassed by the following claims.

In the description above, for the purposes of explanation, numerousspecific requirements and several specific details have been set forthin order to provide a thorough understanding of the embodiments. It willbe apparent however, to one skilled in the art, that one or more otherembodiments may be practiced without some of these specific details. Theparticular embodiments described are not provided to limit theinvention, but to illustrate it. The scope of the invention is not to bedetermined by the specific examples provided above, but only by theclaims below. In other instances, well-known structures, devices, andoperations have been shown in block diagram form or without detail inorder to avoid obscuring the understanding of the description. Whereconsidered appropriate, reference numerals or terminal portions ofreference numerals have been repeated among the figures to indicatecorresponding or analogous elements, which may optionally have similarcharacteristics.

It should also be appreciated that reference throughout thisspecification to “one embodiment”, “an embodiment”, “one or moreembodiments”, or “different embodiments”, for example, means that aparticular feature may be included in the practice of the invention.Similarly, it should be appreciated that in the description variousfeatures are sometimes grouped together in a single embodiment, figure,or description thereof for the purpose of streamlining the disclosureand aiding in the understanding of various inventive aspects. Thismethod of disclosure, however, is not to be interpreted as reflecting anintention that the invention requires more features than are expresslyrecited in each claim. Rather, as the following claims reflect,inventive aspects may lie in less than all features of a singledisclosed embodiment. In another situation, an inventive aspect mayinclude a combination of embodiments described herein or in acombination of less than all aspects described in a combination ofembodiments. Thus, the claims following the Detailed Description arehereby expressly incorporated into this Detailed Description, with eachclaim standing on its own as a separate embodiment of the invention.

The invention claimed is:
 1. An apparatus to provide breathing supportto a patient comprising: a valve comprising at least three ports, saidthree ports comprising an inlet port, a first outlet port and a secondoutlet port, the inlet port adapted for connection to a patientinterface via a primary duct configured for a flow of a gas; at leastone peak inspiratory pressure (PIP) control duct connected to the firstoutlet port of the valve; at least one positive end-expiratory pressure(PEEP) control duct connected to the second outlet port of the valve; atleast two containers wherein a first container contains a first body offluid and a second container contains a second body of fluid, and thePIP control duct is immersed in the first body of fluid in the firstcontainer and the PEEP control duct is immersed in the second body offluid in the second container, and an immersed length of the PIP controlduct is greater than an immersed length of the PEEP control duct;wherein the valve is configured to cycle between the first outlet portand the second outlet port thereby switching the flow of the gas fromthe inlet port to only the first outlet port and from the inlet port toonly the second outlet port; wherein a cycle corresponds to one breath;wherein when the gas flows from the inlet port to the first outlet portof the valve, the gas flows through the PIP control duct, therebycontrolling a PIP in the apparatus so that the patient receives the PIP,and when the gas flows from the inlet port to the second outlet port ofthe valve, the gas in the apparatus flows through the PEEP control duct,thereby lowering pressure in the apparatus to a PEEP so that the patientreceives the PEEP; and wherein if power to the valve is shut off, thevalve remains in an open position to the second outlet port whereby flowof the gas is directed to the PEEP control duct and pressure in theapparatus is maintained at a baseline lower level.
 2. The apparatus ofclaim 1, wherein the valve is a solenoid valve and has a coefficient offlow Cv greater than about 1.5.
 3. The apparatus of claim 2, furthercomprising at least one safety duct adapted for connection to theprimary duct and configured to be immersed in the first body of fluid,wherein an immersed length of the safety duct is greater than theimmersed length of the PIP control duct.
 4. The apparatus of claim 1,further comprising at least one safety duct adapted for connection tothe primary duct and configured to be immersed in the first body offluid, wherein an immersed length of the safety duct is greater than theimmersed length of the PIP control duct.
 5. The apparatus of claim 4,wherein the fluid comprises water.
 6. The apparatus of claim 1, furthercomprising at least one controller communicably connected to the valveto control a rate of cycling of the valve, thereby controlling a numberof breaths per minute, and to control at least one of (a) an inspiratorytime in seconds, (b) a ratio of the inspiratory time to an expiratorytime, and (c) the inspiratory time as a percentage of a cycle time,thereby maintaining the ratio of the inspiratory time to the expiratorytime as determined by a user.
 7. The apparatus of claim 1, wherein thevalve is a solenoid valve.
 8. The apparatus of claim 1, wherein thefluid comprises water.
 9. The apparatus of claim 1, wherein at least oneangled section is connected to a tip of at least one of the PIP controlduct and the PEEP control duct.
 10. The apparatus of claim 1, furthercomprising a pressurized gas supply.
 11. The apparatus of claim 1,wherein a size and a shape of the first container is similar to a sizeand a shape of the second container and location of a tip of the PIPcontrol duct in the first container is similar to location of a tip ofthe PEEP control duct in the second container.
 12. An apparatus toprovide breathing support to a patient comprising: a pressurized gassupply; at least one body of fluid; a primary duct including proximaland distal ends, the proximal end adapted for connection to thepressurized gas supply, the primary duct also adapted for connection toa patient interface between the proximal and distal ends; a valvecomprising at least three ports, said three ports comprising one inletport, a first outlet port and a second outlet port, the inlet portadapted for connection to the distal end of the primary duct; whereinthe apparatus further comprises: (i) at least one peak inspiratorypressure (PIP) control duct connected to the first outlet port of thevalve and configured to be immersed in the at least one body of fluid;(ii) at least one positive end-expiratory pressure (PEEP) control ductconnected to the second outlet port of the valve and configured to beimmersed in the at least one body of fluid; (iii) at least one safetyduct adapted for connection to the primary duct and configured to beimmersed in the at least one body of fluid, wherein an immersed lengthof the safety duct is greater than an immersed length of the PIP controlduct; and (iv) wherein the immersed length of the PIP control duct isgreater than an immersed length of the PEEP control duct; wherein thevalve is configured to cycle between the first outlet port and thesecond outlet port thereby switching a flow of a gas from the inlet portto only the first outlet port and from the inlet port to only the secondoutlet port; wherein a cycle corresponds to one breath; wherein when thegas flows from the inlet port to the first outlet port of the valve, thegas flows through the PIP control duct, thereby controlling a PIP in theapparatus so that a patient receives the PIP, and when the gas flowsfrom the inlet port to the second outlet port of the valve, the gasflows through the PEEP control duct, thereby lowering pressure in theapparatus to a PEEP so that the patient receives the PEEP; and whereinif power to the valve is shut off, the valve remains in an open positionto the second outlet port whereby flow of the gas is directed to thePEEP control duct and pressure in the apparatus is maintained at abaseline lower level.
 13. The apparatus of claim 12, further comprisinga container containing the body of fluid, and the PIP control duct andthe PEEP control duct are immersed in the body of fluid in thecontainer.
 14. The apparatus of claim 12, further comprising at leasttwo containers wherein a first container contains a first body of fluidand a second container contains a second body of fluid, and the PIPcontrol duct is immersed in the first body of fluid in the firstcontainer and the PEEP control duct is immersed in the second body offluid in the second container.
 15. The apparatus of claim 14, wherein asize and a shape of the first container is similar to a size and a shapeof the second container and location of a tip of the PIP control duct inthe first container is similar to location of a tip of the PEEP controlduct in the second container.
 16. The apparatus of claim 12, wherein acontroller is communicably connected to the valve to control a rate ofcycling of the valve, thereby controlling a number of breaths perminute, and to control at least one of (a) an inspiratory time inseconds, (b) a ratio of the inspiratory time to an expiratory time, and(c) the inspiratory time as a percentage of a cycle time, therebymaintaining the ratio of the inspiratory time to the expiratory time asdetermined by a user.
 17. The apparatus of claim 12, wherein the valvehas a coefficient of flow Cv greater than about 1.5.
 18. The apparatusof claim 12, wherein the valve is a solenoid valve and the fluidcomprises water.
 19. The apparatus of claim 12, wherein at least oneangled section is connected to a tip of at least one of the PIP controlduct and the PEEP control duct.
 20. A method of assisting breathing of asubject using an apparatus of claim 16, the subject selected from agroup consisting of an adult, a child, an infant human being and amammal, comprising: (i) connecting the subject to the apparatus of claim16; (ii) initiating a flow of a gas in the apparatus; and (iii)monitoring a number of breaths per minute delivered to the subject. 21.The method of claim 20, further comprising connecting the subject to theapparatus using nasal prongs, a face mask or a nasal mask.
 22. Themethod of claim 20, further comprising setting the flow of the gas atabout 1 to 10 L/min for the infant human being.
 23. The method of claim20, further comprising setting the flow of the gas at about 1 to 30L/min for the adult human being.
 24. The method of claim 20, furthercomprising selecting an immersed length of a PIP control duct and animmersed length of a PEEP control duct based on the subject's uniquebreathing needs.
 25. The method of claim 24, further comprisingcontrolling at least one of (a) an inspiratory time in seconds, (b) aratio of the inspiratory time to an expiratory time, and (c) theinspiratory time as a percentage of a cycle time, thereby maintainingthe ratio of the inspiratory time to the expiratory time as determinedby a user.